In general, a washing machine can automatically perform washing and rinsing laundry by supplying the laundry with an impact attributable to a flow of water.
The washing machine may be classified into a vortex type, an agitator type, and a drum type depending on the washing method. The vortex type washing machine has a pulsator on the lower side of a washing tub and can wash, rinse, and remove excess water from the laundry in the washing tub using rotational force of the pulsator. The agitator type washing machine has a similar exterior to the vortex type washing machine. The agitator type washing machine has an agitator in the washing tub and may reduce damage caused by tangled laundry. The drum type washing machine has a door at the front of the washing machine and can wash the laundry using a relatively small amount of water.
In order to improve washing efficiency, a washing machine including a bubble generation device for supplying air bubbles and/or foam to a washing tub is proposed. When bubbles generated from the bubble generation device flow into the washing tub, the bubbles burst due to contact with the laundry, thereby impacting the laundry. Accordingly, contaminants adhered to the laundry may be effectively removed.
However, the conventional washing machine is problematic in that old stains are not easily removed by the bubbles supplied into the washing tub during the washing process.
A conventional drum type washing machine may be disclosed in Korean Patent Laid-Open Publication No. 2006-0103977, filed on Oct. 9, 2006.